1. Field of the Invention
The present invention relates to a class of fully-cyclized aromatic polyimides, typified as containing alkyl substituted aromatic diamines and/or alkyl substituted halide substituted aromatic diamines. These aromatic polyimides are more soluble in weaker solvents such as toluene than other high-temperature aromatic polyimides.
2. Prior Art
U.S. Pat. Nos. 4,629,685; 4,629,777, and 4,656,116 disclose highly alkyl substituted aromatic polyimides some of which are soluble in good aprotic solvents. They do not disclose these polyimides to be soluble in weaker solvents.
U.S. Pat. No. 3,356,648 discloses polyamide acids and polyimides from hexafluoropropylidene bridged diamines and dianhydrides to be soluble in relatively weak solvents such as acetone but not in weaker solvents such as toluene.
U.S. Pat. No. 3,959,350 describes polyimides soluble in good aprotic solvents. Solubility in weaker solvents is not exemplified.
U.S. Pat. No. 3,705,870 describes soluble polyimides prepared from 2,4-diaminodiphenylamines and 2,4-diaminophenyl sulfides. Solubility in weak solvents is not exemplified.
U.S. Pat. No. 3,705,869 describes soluble polyimides derived from 3,3-bis(p-aminophenyl)oxindole and 3,3-bis(p-aminophenyl)-1-phenyl oxindole. Solubility in weak solvents is not disclosed.
U.S. Pat. No. 3,758,434 describes polyimides which are soluble in good, aprotic solvents. Solubility in weaker solvents is not disclosed.
U..S Pat. No. 3,787,367 describes soluble copolyimides. Solubility in weaker solvents is not disclosed.
U.S. Pat. No. 3,803,075 describes soluble polyimides from 2,6-diamino-s-triazines. The materials are insoluble in weak solvents.
U.S. Pat. No. 3,856,752 describes soluble polyimides prepared from phenylindanediamines and dianhydrides. Solubility in weak solvents is not disclosed.
U.S. Pat. Nos. 4,078,142 and 4,145,522 describe polyimide materials which have improved solubility. However, no solubility information was disclosed.
U.S. Pat. No. 3,546,175 describes soluble polyimides from 2,4-diaminoisopropylbenzene and pyromellitic dianhydride and 3,3',4,4'-benzophenonetetracarboxylic dianhydride. These materials were found to only be soluble in good aprotic solvents.
U.S. Pat. No. 3,642,682 describes soluble polyimides from guanamine-based diamines. Weak solvents may be used as diluents or cosolvents with good, aprotic solvents for their materials.
U.S. Pat. No. 4,588,804 describes a series of soluble polyimides. Solubility in weak solvents is not disclosed.
U.S. Pat. No. 4,607,093 describes soluble polyimides. These materials are disclosed not to be soluble in weak solvents.
NASA-TM-89016 describes soluble polyimides. These materials are not disclosed to be soluble in weak solvents.